1997 Jimmy engine questions

[72shortbed12]

Just picked up a really clean 97 jimmy for $600! It threw a rod through the pan and block so they took an older block and did a full rebuild and bolted everything on minus the oil pan and timing cover. The motor looks great and the paperwork shows a reputable machinist did the work so I'm not worried about it. It has the right crankshaft in it but I've read about issues with the oil pan and timing cover. I know they changed in 96 so will the aluminum pan and plastic timing cover work on the older block? If not what is the best way to go about finishing it? The casting # is 471594 but the number on the pad in front of the passenger side head is wore out to much to be read. It does have a block off plate where the manual fuel pump used to mount. Anyway ideas on the year of the block? Are there any other issues I might run into?

Thanks

[gchemist]

I think everything swapped over unitl 99. In 99 or so, the knock sensor and something else have a different size thread. Read this on variations of the 4.3: http://www.s10forum.com/Rebuilding_the_Chevy_262.htm

[Tink]

If it has the block off plate for the fuel pump, then the block is an 85 or 86. So, no you shouldn't use the plastic cover because it leaks around the bolt holes on the earlier blocks.

[72shortbed12]

So whats the best option for a timing cover with a crank positioning sensor?
Modify an original? I'm new to the 4.3 but I assume this has been done before?

[Tink]

If you have the plastic for a template, then I'd modify the tin cover... What is on the motor now?

[72shortbed12]

The old style metal cover that they welded for the crank sensor port. It looks questionable, there sgorilla glue slapped on the welds.
Has anyone used the plastic cover on the old blocks and not had them leak or is it a just a matter of time?

[68C15]

does the metal cover come almost all the way up to the intake or is it more like an old small block? the tall cover was made in metal and later in plastic. it is taller to accommodate the balance shaft driven off the camshaft. when the went from CFI to CSFI in 96 they switched to the plastic and mounted a crank sensor.

if the sensor is not positioned correctly it won't run. even if you do a CKP relearn.

pull that metal cover off and see if a plastic one fits.

[72shortbed12]

It's the old school cover. They welded brackets on the cover for the sensor and a hold down but I don't trust it. I talked to a local guy who does 4.3 and 5.3 vortec motor swaps into rockcrawlers all the time and he said to sell it as an older motor with vortec heads and buy the right motor from a salvage yard.

[Tink]

Unfortunately, that sounds like the best thing to do....

[72shortbed12]

Picked up a complete motor this weekend out of a 96 full size 1500 with 60k miles for $350. Less than half price than the salvage yards wanted and half the miles. Came with the wiring harness and computer which I don't need so I'll make some money back. So far I've switched a couple sensors off the intake, exhaust manifolds, and motor mounts that I noticed are different. Anything else I need to change before I drop it in?

[68C15]

Originally Posted by 72shortbed12

Anything else I need to change before I drop it in?

intake gaskets using the good metal framed ones from Fel-Pro.

no matter what any parts guy tell you, do NOT use a gasket between heads and exhaust manifolds. clean to bare metal and a skim coat of Ultra Copper RTV at the most. oh, there's a trick to keep the spark plug shields from bending/twisting when you install manifolds. some aluminum anti-seize under the head of the bolts while leaving the shield and manifold dry. then the bolts will turn yet the shield will stay in place "grabbing" onto the manifold. I also like to put a thin layer of the stuff on the NON-THREADED part of the bolt. that way it doesn't rust or bind to the manifold for later removal.

another thing;
these http://www.lislecorp.com/divisions/products/?product=21 almost a must have for used manifolds

[Tink]

How long has the junkyard motor sat? If it has sat for quite a while (over a couple months), it is always a good idea to replace seals/gaskets (headgaskets, rear and front main seal...).

[72shortbed12]

Is the fan different also? The motor has a metal blade fan which is bent and the one I found from autozone is plastic so I'm assuming they're different.
I ordered gaskets for the oil pan and a new timing cover. I've had a few people mention the intake gaskets also so Ill plan on them to. The motor has sat for 3 yrs. If I pull the heads then I'll put on the new set that came with the jimmy.
With only 60k miles on it I was just going to run it and see how it works out.

[72shortbed12]

This is probably a dumb question but if I do swap heads would I dare reuse the head gaskets on the other motor I'm going to sell? I'll put new on the motor I;m going to run but I assume since they ve been torqued down its not a great idea. It hasn't been fired yet. I don't really want to buy two sets of head gaskets.

[68C15]

modern head gaskets are like toilet paper. designed for one time use only but they work very well.
copper head gaskets are like pine cones. clean and reuse as often as you want. they just don't work as well.

[Tink]

Don't know when they switched to the plastic fan... my 2000 had one.

If you are just going to sell the other motor, just let people know they should do headgaskets on it.

[72shortbed12]

I'm thinking about running a taurus fan instead. I'll do the oil pan, timing cover and intake gaskets and see how it does. I am thinking about replacing the freeze plugs. I don't know if they've got corrosion from sitting for so long.